Process for dewaxing hydrocarbon oils



Nov. 25, 1930. A. R. GREIG PROCESS FOR DEWAXING HYDROGARBON OILS Filed Dec. 20, 1927 ffl ww/l :mh/ IIII-,...M.H:nEN\\v/VVW/VVM 5. @Vl

Patented Nov. 25, 1930-v YUNITEDv STATES PATENT OFFICE ARTHUR R. GREIG, OF PORT ARTHUR, TEXAS, ASSIGNOR l'.lOgTHIE TEXAS COMPANY, OF

NEW YORK, N. Y., A CORPORATION F DELAWARE PROCESS FOR DEWAXING HYDROCARBON OILS Application filed 1.December 20, 1927. Serial No. 241,289.

This invention relates to 4a Aprocess and apparatus for the separation of solid and semi-solid waxes from hydrocarbon oils and more particularly refers to a process and ap- 5 paratus involving centrifugal means for separating waxy constituents from hydrocarbon oils.v The invention is concerned with the provision of a centrifugal process and apparatus adapted for continuous operation at high eliciency.

In theI process of separating wax from hydrocarbon oil wherein the wax-bearing oil is first chilled to precipitate the wax and is then passed through a centrifuge, it is found that the centrifugal apparatus generally used for this purpose becomes clogged with the harder portions of wax and with the frozen particles of moisture contained in the oil. Such frozen material tends to adhere to the rotating bowl of the centrifuge which results in a lowering ,in the capacity of the apparatus and also in the reduction of itsefl'lciency of separation. Also it is found in vpractice. that the comparatively restricted opening through which the wax-bearing oil is fed to the centrifuge bowl rapidly becomes clogged with frozenparticles of hardlwax and moisture. Thus under ordinary conditions of operation it will be found necessary to completely dismount and clean the usual commercial type of centrifuge machine after periods of operation varying from four to six yhours whenA employed in the dewaxing of hydrocarbon oil.

member in the form of a cast iron bowl adapt- The present invention provides a method ed to be mounted upon suitable foundations.

The base member is fitted with suitable bear-l ing elements upon which is mounted a rotatable bowlvll. A motor 12 or other suitable source of lpower operates upon the bowl 11 causing it to revolve at high speed. Oil is introduced into the apparatus at the lower end of the bowl through the pipe 13 and the `wax particles to be yforced outward against the wall of the bowl while the wax freed oil tends to remain near the center of the bowl. Thus the wax-bearing oil is continuously charged into the lower portion.of the bowl and flows upward, at the same time undergoing separation so that, through proper separating means at the upper end of the bowl, the wax" and oil are withdrawn in separate streams.

In such operation, which may ordinarily be carried on at temperatures well below zero'Fahrenheit, particles of hard wax and moisture become frozen upon the walls of the rotating bowl. This reduces the internal diameter of the bowl which in turn reduces the centrifugal force generated by the rotation of the bowl and seriously impairs the eliciency of the separation process. The same type of material also tends to collect in the restricted opening of the charging nozzle thus cutting down the quantity of Wax-bearing oil which it is possible to charge to the apparatus. By the practice of the present invention such difficulties are overcome in the following manner.

Periodically, say for example every two or three hours, the flow of chilled wax-bearing oil to the ap aratus is interrupted by closing the valve 1 fitted in the oil feed line.

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The valve 17 is then opened, which serves to introduce a heating medium, such for example as steam or hot water, through the charging nozzle into the centrifuge bowl. Ordinarily the admission of steam over a period of only one 'or two minutes is required to completely free the apparatus from accumulations of congealed wax and ice after which the steam flow is cut off by closing the valve 17 and the feed of chilled waitbearing oil to the apparatus is resumed. In .eneral the time of steaming necessary to ree the apparatus from the accumulation of frozen wax and water is not sufficient to appreciably heat up the centrifuge bowl and it is found that upon continuing the charge of chilled oil to the apparatus there is no appreciable loss of refrigeration and consequent incomplete separation of wax and oil. It can readily be seen that the application of the invention to the removal of wax from hydrocarbon oil in connection with centrifugal process and apparatus accomplishes a very desirable economy in operation. Thus under ordinary methods a medium sized commercial installation employing one-half dozen or more centrifugal machines would require the entire services of one man in dismounting and cleaning the centrifuges. Under such conditions each centrifuge would be idle for a period of perhaps several hours during the day and as a result of the frequent dismounting would be subjected to considerable wear and depreciation. By the practice of the present invention cleaning an entire battery of centrifuges requires only a few minutes of the operators time, causes troduction of steam until accumulations of solidified wax and moisture are removed after introducing a heating medium intol ythe centrifuge during its operation at the point wherein the wax-bearing oil is normal- 1y introduced, until accumulations of solidilied wax and moisture are substantially removed from the apparatus.

In witness whereof I have hereunto set my hand this 2nd day of December, 1927. ARTHUR R. GREIG.

no wear upon the apparatus and the time during which theindividual machines are ino erative is negligible.

bviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof and, therefore, onlysuch limitations should be imposed as are indicated in the appended claims.

What I claim is: 1. The method of operating centrifugal apparatus engaged in the separation of wax from a chilled body of hydrocarbon oil which comprises introducing a heating medium ,into the centrifuge periodically during its operation at the point wherein the ywax-bearing oil is normally introduced and continuing the introduction of the heating medium until accumulations of solidified .wax and moisture are removed from the working surfaces of the apparatus.

2. The method of operating centrifugal apparatus engaged in the separation of wax from a chilled body of hydrocarbon oil which comprises introducing steam into the centrifuge periodically during its operation at the point wherein the wax-bearing oil is normally introduced and continuing the ini iso 

